The present invention is generally related to piece good conveyance and, more particularly, a method and device for horizontally positioning for onward conveyance a large number of identical or similar flat objects that are supplied in a serial stream.
One example of an application, in which serially supplied, flat objects are positioned horizontally on a conveying device, is the collating of parts of printed products to form stacks of part products. The collated stacks are then each processed into a finished printed product (e.g., a book or a brochure), usually by binding or stapling. For such a collating operation, for example, a conveyor belt is utilized as a conveying device, with either transverse walls or toes (catches) at a distance to one another in the conveying direction and dividing the conveying track into conveying compartments of equal size. These conveying compartments are transported either continuously or in a clocked cycle past a row of feed points arranged one behind the other. At each of the feed points a part product is deposited in every passing conveying compartment, so that during transportation along the conveying track a stack of part products is produced in every conveying compartment. At the end of the stack conveying track, each of the stacks has a number of part products equivalent to the number of the active feed points it has passed.
Instead of using the named conveyor belt with conveying toes (catches) or transverse walls, the stacks in production can also be pushed along a suitable base by transport cams (catches). Such pushed conveying can be carried out continuously or in a clocked cycle alternating with standstills.
For the supply and horizontal positioning necessary in the mentioned application example, the flat objects are usually conveyed toward a feed point parallel to their main surfaces and one after the other or overlapping one another and they are pushed onto the onward conveying device, resp., onto a stack of other flat objects being transported past the feed point with the help of the onward conveying device. The feeding direction for this purpose is directed toward the onward conveying direction from above and advantageously intersects the plane (conveying plane), on which the conveyed objects are lying, at an acute angle.
In the case of clocked onward conveyance, for which, for example, conveying compartments are stopped for feeding steps and are transported on between feeding steps, the supply direction can be relatively freely selected relative to the onward conveying direction (projection of the supply direction into the onward conveying plane). This means that the supply direction, for example, can be transverse to the onward conveying direction (transverse supply) or it can be the same as the onward conveying direction (parallel supply). In the case of continuous onward conveying, supply of the latter type is particularly suitable, i.e. supply with a feed direction lying in the same plane perpendicular to the onward conveying plane as the onward conveying direction and approaching the onward conveying line from above and at an acute angle.
In the case of square or rectangular, flat objects being supplied by transverse supply, the edges being directed downstream in the supply stream are positioned on the one side of the onward conveying means opposite the feed and they are oriented parallel to the onward conveying direction. In the case of a parallel supply, the edges being oriented downstream in the supply stream remain the leading edges on onwards conveyance being aligned perpendicular to the conveying direction. For flat objects with other shapes, the same applies in analogy for corresponding edge zones.
Known devices for collating printed products, for example, comprise sheet feeders for supplying the part products. Usually these sheet feeders are supplied with part products by hand, the part products being deposited in a stacking shaft. From the stacking shaft the part products are decollated to form a conveying stream. In this stream, they are conveyed toward the feed point essentially parallel to their main surfaces one after the other or overlapping one another and they are pushed onto the stacks under production. This means that the position of the products on the stacks under production is correlated in a fixed manner with the position of the products in the stacking shaft. Therefore, for a predefined product position on the stacks being produced, the products have to be filled into the stacking shaft in a corresponding manner.
It is also known to supply feed points by uncoiling stations, in which stations a stream of imbricated printed products is uncoiled from a corresponding coil and is supplied to the feed point. Feeding by means of a continuously supplied product stream is also known. In both cases it is advantageous to interpose a buffer between the feed point and the supply device. For such equipped feed points also, there is a fixed relationship between the product orientation in the supply stream and the product orientation on the stacks being produced by collating. If this correlation is to be changeable, then devices have to be provided, with which the supply stream of imbricated products can be reorganized, i.e., re-scaling devices, e.g. for reversing the stream or for recoiling a product coil. Devices of this kind are expensive and take up a lot of space.
It is also known to produce stacks from a plurality of different printed products, such as newspapers, magazines, advertising brochures and other advertising material using a collating device and then package the stacks to form complete shipping units e.g. using a folio assembler. In shipping units of this kind the orientation of the individual products is not predefined, as is the case for a stack of part products to be assembled to form one product. On the contrary, there is the desire to arrange the two outermost products of the stack such that the front side of both is visible through the folio, and to arrange the products inside the stack such that thicker folded edges are distributed as uniformly as possible over two opposite sides of the stack to stabilize the stack. Because usually only relatively small numbers of the mentioned shipping units with the same composition have to be made up, this signifies that the supply orientation of the products has to be changed time and again.
With the known supply systems, such changes have to be carried out by persons operating the sheet feeders by filling the products into the stacking shaft with varying orientations depending on the shipping units to be produced. This quite invariably leads to mistakes. Other supply systems have to be correspondingly retooled for such changes and then set up or adjusted for the change. As already mentioned above, this is expensive.
An object of the present invention is a method and a device by means of which flat objects, which are supplied in a serial conveying stream, can be horizontally positioned for an onward conveyance, wherein with the same orientation of all objects in the supply stream it shall be possible, with the simplest of measures, to set two different orientations for the objects onward conveyance. In achieving the objective, the method is designed such that it can be carried out with a simple device, which can easily be adjusted for two positioning orientations.
In accordance with the present invention, flat objects are supplied in suspended manner and with their main surfaces vertical or inclined (not parallel) to the feeding direction such that one of their main surfaces is facing downstream and the other one is facing upstream. This means that the flat objects in the supply stream are held individually or, if required, in small groups by grippers by an upper edge zone. Lower edge zones are movable in the feeding direction relative to the upper edge zones as a result of a corresponding flexibility of the objects and/or of a corresponding ability of the grippers to swivel. This means that, by using appropriate means, the objects can be brought into positions in which the lower edge zone of each object is not situated vertically below the upper edge zone held by a gripper, but rather is either ahead of or trails behind the upper edge zone.
Immediately before the horizontal positioning of an object, a positioning device engages the lower edge zone of the objects and accelerates or retards this lower edge zone versus the upper edge zone in dependence of the desired positioning orientation. As a result of this, the object is brought into an inclined position relative to its vertical position, which it assumes in freely suspended conveyance. When the object is sufficiently inclined, it is released by the gripper and is finally positioned by the force of gravity and, if required, guided by the positioning means.
If, before positioning, the lower edge zone is accelerated versus the upper edge zone, the one main surface of the flat object that was facing downstream in the supply stream is facing upwards after positioning. On the other hand if, before positioning, the lower edge zone, however, is retarded, then the one main surface that was facing upstream in the supply stream is facing upwards.
Onward conveyance, as in the case of the known methods briefly described above, can be clocked or continuous. In the case of clocked onward conveyance, in which the objects are essentially positioned on a conveying surface that is stationary at this point in time, the feeding, for example, can be transverse to the direction of onward conveyance or parallel to it. In the case of continuous onward conveyance, feeding has advantageously substantially the same direction as onward conveyance. For parallel feeding, a lower edge zone accelerated prior to positioning becomes the leading edge zone for onward conveyance; a correspondingly retarded edge zone becomes the trailing edge zone.
The device of the present invention includes a supply means and a positioning means, both being matched to an onward conveying means.
The supply means supplies the flat objects in a suspended position in a controlled manner. For this purpose, it has a multitude of grippers displaceable under control in the feeding direction. Advantageously, these grippers are relatively freely swivellable in the feeding direction. The grippers, for example, are attached to a circulating conveying organ at a regular distance from one another. The grippers, however, can also be displaceable more or less independent of one another and, for example, can be buffered ahead of the feeding point and called up from the buffer specifically for the feeding operation.
The supply means furthermore comprises deactivation means, through which the grippers are deactivated at a predefined release point for releasing the objects. The deactivation means can be controlled such that only a predetermined part of the grippers is deactivated, while not deactivated grippers pass the release point without releasing the object they are gripping.
The positioning means serves to retard or accelerate lower edge zones of objects conveyed by the supply means prior to positioning. The positioning means, for example, is designed as a conveyor belt, which extends underneath the grippers and which forms an acute angle with the feeding direction, the apex of which is in the area of the release point. The speed with which the positioning means moves the lower edge zones bward the release point is adjustable to a minimum of two values. In this respect, one of these speeds for accomplishing an acceleration of the lower edge zones is greater than the conveying speed of the feeding means and the other one for a corresponding retardation is smaller than the conveying speed or else can be zero. If so required, the position of the positioning means is adjustable relative to the supply means.
The supply means and the positioning means are matched to one another and to the onward conveying means such that an object, when it is released by the gripper, has an inclined position. This inclination has such an extent, that the object can be positioned at the predetermined point of the onward conveying means (e.g., in a conveying compartment) having the predetermined orientation (leading or trailing main surface on top) by the effect of the force of gravity and if necessary with controlled assistance by parts of the positioning means.